Mechanical release devices that are actuated when a predetermined pressure is released are many and varied in design. The releases generally are used to separate from a ballast or a float so that a package of interest can be recovered or otherwise deployed. Piston-type release devices using shear pins that are responsive to specific pressures have relied upon springs and the like to perform the separation function once a predetermined pressure is reached. A more sophisticated, double action pressure release device of U.S. Pat. No. 4,571,788 is activated at a deeper depth and comes apart at a lesser depth. The pressure release appears to be relatively uncomplicated and has a piston provided with a sliding seal that moves along a relatively long bore within a housing to effect the flooding of the housing after a predetermined lesser depth is reached. The sliding seal exposes its sealing surface to the corrosive effects of the ambient so that its reliability may be questionable under certain circumstances. The release appears to be depth limited insofar as high pressures of greater than 10,000 psi apparently cannot be withstood. The actuation of the pressure release could be influenced by load accelerations that may prematurely actuate the device, decelerations could retard its timely operation or other hydrodynamic influences on the load may influence the release. Since the parts separate upon actuation, reuse may be difficult.
Thus a continuing need exists in the state of the art for a mechanical release that is set at one pressure and actuated at another and which is reusable and not overly affected by environmental and dynamic influences associated with the load.